JP2010505674A - Fireproof gypsum panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gypsum panel having an improved fire resistance which has a fire resistant layer which can be used on a gypsum panel which is expanded to improve fire resistance, and which does not require a large amount of a normal expansion material.
A core comprising gypsum and a high temperature shrink resistant material and formed into a panel having at least two opposite faces and two opposite edges; one or more of the faces, one or more of the edges and An intumescent layer covering at least a portion of the group consisting of these combinations and comprising a gypsum matrix having a higher density than the core and a first intumescent material; and a surface finish material covering at least a portion of the inflatable layer A multilayer gypsum panel consisting of
[Selection] Figure 1

Description

  The present invention relates to gypsum panel products and methods of making the same. More particularly, the present invention relates to a gypsum panel having improved fire resistance using an expanding surface layer.

  Gypsum panels are a well-known building product that has been used for many years. They are mainly used as inner wall and ceiling products, but also to some extent as external products. A slurry comprising calcium sulfate hemihydrate and water is used to form the core and is deposited on a paper cover sheet that continuously moves under the mixer. A second paper cover sheet is applied thereon and the resulting assembly is formed into the shape of a panel. Calcium sulfate hemihydrate or stucco (stucco) reacts with enough water to convert hemihydrate stucco into a matrix of linked calcium sulfate dihydrate crystals that harden and firm Make things. The continuous strip formed in this way is carried on a belt until the calcined gypsum is cured, and the strip is then cut to form a board of the desired length, which board is placed in a dry kiln. Carried to remove excess moisture.

  Chemically bound water in the dihydrate acts on the fire protection of the gypsum panel. When exposed to heat or fire, the dihydrate converts to the hemihydrate or even to the plaster form. Excessive hydration water is expelled in the form of water vapor. When the water vapor leaves, the heat energy from the fire is used to generate the dehydration reaction and to evaporate the water, so the heat transmission through the panel is reduced. Thick gypsum panels are more fire-resistant than thin ones because heat can penetrate the entire thickness of the panel and expel all crystal water.

  Crystallized water loss usually causes the gypsum to shrink. Because much of the water of crystallization is lost and the original firmly fixed connected gypsum matrix loosens, the gypsum product also tends to become very brittle upon combustion and loses its strength and integrity. Large tears are formed in the gypsum panel due to shrinkage. Shrinkage also widens the opening between the panels joining at the edges. The expansion of the edge bond, large crevices and other openings facilitate the transmission of heat and hot gas through the walls, and also the fire reaches the wood studs behind the gypsum panel and intensifies the fire.

  The introduction of certain fibers, ores and / or inorganic particles into the gypsum core is known to improve the fire resistance of gypsum panels. The use of glass fiber to maintain the strength and integrity of the panel is taught in US Pat. This patent also reveals the addition of calcium sulfate dihydrate to the core slurry to reduce shrinkage.

  The introduction of inflatable materials into the gypsum cores of the panels has also been used as a way to improve the fire resistance of these panels. As the board temperature rises due to the presence of fire, the at least partially expanded material replaces the water being replaced. Compared to a non-expanded gypsum core, it takes a much longer time for the board to burn out or to form a large tear. However, using materials that swell over the gypsum core is relatively expensive, and organic additives require a high amount of use to be homogeneously dispersed throughout the gypsum slurry, so that health and Raise environmental concerns.

  It is well known to those skilled in the art to add perlite and / or vermiculite to a wallboard for fire resistance. Patent Document 2 discloses addition of perlite and vermiculite to a gypsum board. This document teaches that these materials are expandable and expand when exposed to fire. Glass fibers are also optionally added to the core composition. The distribution of glass fibers in the wallboard with increased edge concentration is disclosed in US Pat. U.S. Patent No. 6,057,031 teaches the production of gypsum compositions that combine gypsum, paper fibers and one or more performance enhancers such as inorganic fibers, clays, vermiculite and polymeric binders. None of these references show a core and coating combination that works together to improve resistance.

  A fire test of a wall or floor / ceiling assembly merely measures the time it takes for the system to reach the limit criteria specified in the standard ASTM (The American Society for Testing and Materials) E119 test procedure. For wall assemblies, the limiting criteria are: the passage of thermal energy through the wall, a temperature rise above a predetermined temperature on the surface of the wall that is not exposed to fire, a wall that can withstand a superimposed designed load Defined as the ability to burn through (for walls to withstand loads) or radiation of water through the assembly. According to ASTM C36, a 5/8 inch (16 mm) type X panel is applied to a single layer on each side of the wood / spar wall that will withstand the load when tested according to ASTM E119. Sometimes it must be more than 1 hour refractory point. A 1/2 inch (12 mm) Type X panel must provide a 45 minute fire rating in the same assembly.

  A second type of refractory gypsum panel (modified Type X), known as Type C, provides better performance. In addition to glass fiber additives, Type C panels contain special materials that expand due to the presence of heat, somewhat offsetting panel shrinkage resulting from gypsum dehydration and melting. This increases the stability of the gypsum core and significantly improves the fire performance of the panel.

US Pat. No. 4,647,486 US Patent 3,376,147 US Pat. No. 3,462,341 US Pat. No. 5,601,888

  Those skilled in the art seek gypsum panels with improved fire resistance that do not require large amounts of conventional intumescent materials. Also, those skilled in the art are seeking a fire resistant layer that can be used on a gypsum panel that expands to improve fire resistance.

  These and other requirements are solved by a gypsum panel having a core comprising gypsum and a high temperature shrink resistant material. The core is formed into a panel having at least two opposing faces and two opposing ends. At least one of the edges and / or faces is covered with a swelling layer comprising a gypsum matrix having a higher density than the core and an expandable material. The material used for the surface covers at least a portion of the expandable layer.

  A method of continuously forming a multi-layer panel includes making a gypsum slurry and then dividing the gypsum slurry into at least a primary gypsum slurry and a secondary gypsum slurry. An additive slurry having water and an expanding material is made and added to the secondary gypsum slurry to make an expandable layer slurry that extends over all or at least a portion of the surface finish material. The primary gypsum slurry is spread over the surface finish material and the expanding layer to form a core.

  If desired, other layers or edge coatings are applied to the expanding layer for additional fire protection. The end coating includes a second expanding material. While on fire, the end coating expands and seals the gap between the gypsum panels that join.

  For the expanding material used, its addition to the expanding layer rather than the core slurry increases the thickness, thereby improving fire resistance. If equivalent fire resistance is desired, the amount of material that expands can be reduced, thereby reducing the cost of the material.

  Reducing the amount of additive to the gypsum panel also reduces the overall weight of the product. In addition to limiting the amount of additive and saving costs, reducing the weight of the panel will also reduce shipping costs and reduce the fatigue of operators who carry or install the panel.

It is a cross section of the base | substrate and gypsum panel of this invention. 2 is a cross-section of a gypsum panel of the present invention showing it having an optional edge coating.

  In FIG. 1, the present invention includes a multilayer gypsum panel, generally referred to as 10, which includes a core 12, an expanding layer 14, and a surface finish material 16. This includes including additional layers or covers on the panel. The gypsum panel 10 includes at least two opposing faces 20,22 and two opposing ends 24,26. During the manufacture of gypsum panels, continuous strips of core material 12 are produced that are cut to form individual panels, generally 30. Each panel 30 preferably includes at least two sets of opposite ends. There is a set of opposed cut ends (not shown) where the panels 30 are separated from each other, and a set of opposed final ends 24,26.

  The panel core 12 is made from a primary gypsum slurry containing calcium sulfate hemihydrate, a shrink resistant material and water. A second slurry containing the same components is used to create the expanding layer 14. Details of each component in each slurry and their respective amounts are detailed below.

  An essential component of both the panel core 12 and the expanding layer is gypsum, also known as calcined gypsum, clay or calcium sulfate dihydrate. Gypsum is made into panels by adding water to a stucco, also known as plaster of Paris, calcined gypsum or calcium sulfate hemihydrate, to form a slurry. Calcium sulfate hemihydrate forms a crystalline matrix of calcium sulfate dihydrate that is hydrated by water and connected. Any calcined gypsum containing calcium sulfate hemihydrate, calcium sulfate anhydrite or both is useful for any slurry.

  Calcium sulfate hemihydrate produces at least two common crystal forms, the alpha and beta forms. Beta calcium sulfate hemihydrate is commonly used for gypsum board panels, but alpha calcium sulfate hemihydrate or panels made from alpha and beta hemihydrate are also considered useful in the present invention. It is done. Beta fired plaster is a preferred calcium sulfate hemihydrate in both primary and secondary slurries. It is conceivable that the anhydrite is used as a low-calcined gypsum component, preferably in an amount less than 20% by weight of the calcined gypsum content in both slurries.

  Gypsum composites change their silica content and the amount and type of soluble salts present in the deposit. These deposits are generally not removed before firing and are therefore present in calcium sulfate hemihydrate. The presence of certain low melting point soluble salts, especially chloride, lowers the melting point of gypsum composites and causes dramatic high temperature shrinkage. The melting of the gypsum composite has been confirmed by SEM inspection. The high soluble salt content in the gypsum composite lowers the melting point and increases the gypsum shrinkage. Preferably, the soluble salt content is less than 0.2% by weight.

  Another desirable property of the stucco is the high silica content, with the preferred silica being a clay mineral such as kaolin clay. A stucco having a high silica content in the gypsum composite raises the melting point. This is preferred for better fire resistance. Examples of high silica calcium sulfate hemihydrate are greater than 1 wt% silica or greater than 2 wt% clay content.

  In a preferred embodiment of the invention, both the core 12 and the expanding layer 14 comprise at least 50% by weight of the calcium sulfate hemihydrate of the dry ingredients. More preferably, the core 12 comprises at least 60% by weight calcium sulfate hemihydrate, more preferably 70-99% by weight. A preferred amount of stucco in the wick 12 is about 70 to about 90% by weight based on the weight of dry solids.

  The expanding layer 14 is often less than stucco in weight percent because it has at least one additional part. The amount of plaster in the expanding layer 14 preferably ranges from 60 to about 90% by weight, based on the weight of dry solids in the slurry.

  Another essential component of both the core 12 and the expanding layer 14 is a high temperature shrink resistant material. Any material that can be used with the other ingredients and does not shrink is useful as the shrink resistant material. The most shrink resistant materials are fillers that raise the melting point of the gypsum composite to reduce or prevent shrinkage at high temperatures. By replacing the stucco with a small amount of these fillers, the cured core 12 does not shrink much compared to cured cores without these fillers. Examples of shrink resistant materials include glass fibers, glass or synthetic fibers, fumed silica, diatomaceous earth and clays such as kaolin clay. Many silica-rich minerals act to reduce gypsum shrinkage. Preferably, the core does not include a material that expands due to cost concerns. The shrink resistant material is used in an amount of 0.1 to about 3% by weight based on the dry ingredients. A preferred shrink resistant material is kaolin clay. Note that not all glass fibers are shrink resistant. Only shrink resistant materials are useful with this component.

  In addition to the shrink-resistant material, glass fibers (usually 1 / 2-3 / 4 inch long and 10-16 microns in diameter, melting point 800 ° C. or higher) are added to the gypsum core and the expanding layer for both surface finishes. Even after the paper burned off on fire, the entire gypsum panel was held together (ie retained integrity).

  The fourth essential component of the gypsum core 12 and the expanding layer 14 is water. During the production of gypsum articles, water exists as a liquid. Stucco and shrink resistant materials are added to water to form a slurry. Preferably, the water is as pure as possible to reduce side reactions. As mentioned above, the presence of certain salts can modify the rate of hardening of the gypsum as well as its tendency to shrink. Limiting the amount of salt introduced with water makes it easier to control the cure time and product shrinkage.

In some optional aspects of the invention, one or more additives are included in either the primary gypsum slurry, the secondary gypsum slurry, or both. Concentrations are reported in quantities per 1000 square feet (93 m ² ) of finished board panels (“MSF”). Cure retarders (within about 2 Lb / MSF, about 9.7 g / m ² ) or accelerators (within about 35 Lb / MSF, about 170 g / m ² ) are added to modify the rate at which the hydration reaction occurs. “CSA” is a set accelerator consisting of 95% calcium sulfate dihydrate ground with 5% sugar and boric acid and heated to 250 ° F. (121 ° C.) to caramelize the sugar. CSA is available from USG Corporation, South, OK Plant and is made according to US Pat. No. 3,573,947, which is hereby incorporated by reference.

  In addition, the composition of the core 12 and / or the expanding layer 14 optionally includes starch, such as pregelatinized starch or acid-modified starch. Inclusion of pregelatinized starch increases the strength of the hardened and dried gypsum cast and allows the paper under conditions of increased moisture (eg, for increased water to calcined gypsum) conditions. The risk of peeling can be minimized or avoided. One skilled in the art will understand how to pregelatinize the raw starch, such as cooking the raw starch at a temperature of at least about 185 degrees Fahrenheit (85 ° C.) or other methods. Suitable examples of pregelatinized starch include PCF 1000 starch (commercially available from Burger Milling Inc.), and AMERIKOR 818 and HQM PREGEL starch (both commercially available from Archer Daniels Midland Company), It is not limited to these. If included, the pregelatinized starch is present in any suitable amount. For example, if included, the pregelatinized starch is added to the mixture used and is present in an amount of about 0.5 to about 10% by weight of the hardened gypsum composition. Form things.

Other optional ingredients may be used to modify one or more properties of the final product core 12 and / or the expanding layer 14 and paper fibers within 15 Lb / MSF (within about 73 g / m ² ) are also added to the slurry. Is done. Dispersants or surfactants are common additives that modify the viscosity or surface properties of the slurry. Naphthalene sulfonate is a preferred dispersant, such as DILOWLOW ™ from Geo Specialty Chemicals, Cleveland, OH. Preferably, the dispersant is added to the core slurry in an amount within 16 Lb / MSF (within 78 g / m ² ). The wax emulsion detailed below is added to the gypsum slurry in an amount within 20 gallons / MSF (within 0.8 L / m ² ) to improve the water resistance of the finished gypsum board panel. Pyrithione salts are useful in addition to other preservatives. When pyrithione salts are used with any other additive, no harmful effects are known. As such, pyrithione salts are considered useful when combined with any additive that is added to the gypsum core to modify other properties of the cured gypsum core 12.

  In embodiments of the present invention that use foaming agents that create voids in the hardened gypsum-containing product to reduce weight, any conventional foaming agent known to be useful in producing foamed hardened gypsum products. Can be used. Many such blowing agents are well known and commercially available, for example, from GEO Specialty Chemicals, Ambler, PA. A preferred method for producing foam and foamed gypsum products is disclosed in US Pat. No. 5,683,635, which is incorporated herein by reference. If a blowing agent is used, the foam is preferably generated separately from the gypsum slurry. The pre-generated foam is then injected into the slurry the next time the slurry exits the slurry mixer. The entire slurry is discharged from the mixer. When it exits or immediately after exiting, the slurry is divided into at least two parts. The foam is pumped into at least one of the slurry streams forming the gypsum core 12. The flow of slurry and foam is in the flow that then becomes the gypsum core 12. No additional mixing is necessary after addition of the foam. The foam and slurry are thoroughly mixed as they move through the hoses and conduits to the forming table.

  In some embodiments, a trimetaphosphate compound is added to the gypsum slurry used to create the core 12 and / or the expanding layer 14 to increase the strength of the product and reduce the sagging resistance of the cured gypsum. Preferably, the concentration of the trimetaphosphate compound is about 0.1 to about 2.0% by weight, based on the weight of the calcined gypsum. A gypsum composition comprising a trimetaphosphate compound is disclosed in US Pat. No. 6,342,284, which is incorporated herein by reference. Examples of trimetaphosphate salts include sodium, potassium or lithium salts of trimetaphosphate, see, for example, Astaris, LLC, St. Some are available from Louis, MO.

  The slurry can be produced by any method known by those skilled in the art. In a preferred embodiment, each of the slurries is made by mixing moisture free components such as calcium sulfate hemihydrate and a shrink resistant material. The water-containing component, if present, is added directly to the water. The moisture-free component is then added, mixed and dispersed to the water-containing component in a continuous manner.

  Mixing of primary and secondary slurries in separate mixers is contemplated. However, in other embodiments, when the common slurry is mixed and dispersed from the mixer, it is divided into a primary slurry and a secondary slurry. This is because the expanding layer 14 is made from a secondary gypsum slurry that is very similar to that used in the primary gypsum core 12. The secondary slurry can be obtained as a slip stream of the primary slurry or it is assembled separately. When the slip stream is taken from the primary gypsum slurry, it is preferably taken as the primary slurry exits the slurry mixer.

  The density of the secondary slurry is preferably higher than that of the gypsum core 12. The high density nature of the secondary slurry can be achieved in many different ways. Preferably, the density of the secondary slurry is increased by reducing the total void volume of the secondary slurry. In one embodiment, the secondary slurry is produced without the addition of foam. Other embodiments add less foam to the secondary slurry than is contained in the primary slurry. With less foam, there is less air associated with reducing the density of gypsum. In yet another aspect, the same amount of foam is added to both the primary slurry and the secondary slurry, and the secondary slurry is then subjected to treatments such as stirring, crushing, etc. to break some of the foam, This increases the density compared to the primary slurry.

  The expanding material is added to the secondary slurry. Expanding materials undergo chemical or physical changes when exposed to expanding heat or flame. Some minerals, such as perlite or vermiculite, swell like popcorn when water is detached from their crystals by heat and the rift suddenly expands. Other materials, such as expanding polymer systems, form an expanding foam that becomes viscous and then cures into a dense, thermally insulating foamy charcoal. However, care must be taken that the polymer expands reliably under normal fire conditions. Expandable graphite is also used as the expanding material. Perlite, mica and vermiculite are preferred examples of materials that expand due to their reasonable cost and availability.

  The amount of material that expands depends on the material itself chosen. When vermiculite is used, it is preferably used in an amount greater than about 5% to 20% by weight based on the weight of the secondary slurry as the expanding material increases.

  A preferred embodiment of the present invention includes a firecode gypsum panel 10. Type X or refractory gypsum panel 10 includes chopped glass fibers blended into an additive such as a gypsum core 12. These additives, when exposed to fire and after the facing paper 16 burned out, bridge the gypsum crystals and the tears formed when the panel water is converted to water vapor. Works to reduce size. This prolongs the integration of the panel 10 and keeps it acting as a refractory barrier, thereby delaying the passage of heat through the wall or ceiling assembly.

  The expanding layer 14 covers at least a portion of at least one of the surfaces 20, 22, at least one of the ends 24, 26, or a combination thereof. The inflating layer 14 is preferably applied to at least one of the edges 24, 26, or the panel surfaces 20, 22 near the edges. When exposed to a heat source such as fire, the expanding layer 14 expands and fills the void left by the evaporating water, thickens the panel 10, seals the space between the panels, and forms in the panel. It seals the rift, fills the space, reduces the opening of the end joint, and helps make it more difficult for fire or hot gas to pass through the exposed panel. The area that seems to benefit most from the expanding layer 14 is one of the edges 24, 26 adjacent to the edges 24, 26 of the adjacent panel 10 and the surface finish within a few inches of the edges 24, 26. Above and / or near the fixture 32 that secures the panel 10 to the base 34. If desired, the expanding layer 14 is thick near the edges 24, 26 of the panel 10.

  The amount of expansion expected depends on the type and amount of expansion material added to the expanding layer 14 and the thickness of the expanding layer itself. As the thickness of the expanding layer 14 increases, the amount of expansion also increases. Preferably, the expanding layer 14 is applied in an amount of 20 to about 250 mils thick. Thicker coatings are also useful, but increase the cost of the product. At the preferred coating level, an expansion of the expanding layer 14 of greater than 1/8 inch is obtained. The desired component in the expanding layer 14 is all commercially available expanding coatings.

  In FIG. 2, an end coating 40 is applied to at least one of the ends 24, 26 as desired. This end coating 40 is a second expanding material that expands and seals the gap 42 between adjacent panels 10. Other components of the end coating 40 include water, but also include the addition of the desired material to the end coating 40. Any expanding material is useful as the second expanding material. Preferred second expanding materials are vermiculite and / or mica. The second inflating material is an inflating material that is the same as or different from the first inflating material. Preferably, end coating 40 includes only water and a second expanding material.

  The facing material 16 is optionally placed outside all layers of one or more faces 20, 22 and / or one or more edges 24, 26 of the panel 10. Use of the surface finish 16 increases the bending strength of the panel 10. Any material known to be used as the surface finish 16 is useful. Paper is a very common surface finish material 16. Multilayer paper is particularly preferred when one or more layers of kraft paper are used and have one or more layers of manila paper on the surface. Manila paper is particularly used on layers that are directed to residential areas. Other surface finish materials are also suitable, including polymer sheets and sheets made from fibers such as glass fibers. The production of gypsum panels without surface material is also included.

  Either one or both of the surfaces 20, 22 are covered with a surface finish material. When both surfaces 20, 22 are covered, one surface is preferably covered with a first facing paper, while the second surface is covered with another surface finishing material, such as a second facing paper. Often, the first and second facing papers are different, but panels with the same facing material on both sides 20,22 are also included.

Test boards were made according to the recipe in Table 1. Water was weighed and placed in a large Waring blender mixing vessel. The moisture free ingredients were weighed and mixed together and then added to the liquid in the blender container. After dipping for 10 seconds, the blender was moved for 10 seconds to sufficiently mix components without moisture into the liquid to form a slurry. A sample board was made by casting the slurry into a 12/8 inch (30.5 cm) by 14 inch (35.6 cm) high 5/8 inch (16 mm) mold. Excess slurry was scraped from the top of the mold. The weight of the board is reported as a weight per 1000 square feet (93 m ² ).

  12 inch x 14 inch (30.5 cm x 35) using a Delta 12 inch (30.5 cm) bench drill press (Delta International Machinery Corp. Jackson, TN) and a 4 inch (10.2 cm) diameter "crumper". .6 cm) board samples were cut from the center. A 4 inch (about 10 cm) diameter disc was taken from the board samples made in each laboratory. The drill was run at low speed to smooth the cut surface of the sample. Due to errors in the measurement of the diameter of the disc, it was avoided that there were non-smooth edges around the sample. Both the thickness and the outer diameter of each disc were measured twice using a Mitsutoyo Digimatic caliper (Mitsutoyo America Corp. Aurora, IL) prior to testing to make accurate measurements. Each sample was measured twice, ie, once at each of the two positions approximately perpendicular to each other, and the two measurements were averaged.

  Six disc samples were placed in a 2x3 pattern on the oven floor for each fire test. Samples were placed in an electrically enclosed Lindberg / Blue M 1100 ° C. Moldotherm Box furnace (Lindberg / Blue M, Asherville, NC) with a digital 16 segment programmable controller. The furnace was placed in a conventional laboratory hood and the combustion gases generated during the test were ventilated for safety.

  The furnace temperature was programmed to gradually increase to a temperature of 850 ° C., maintain that temperature for 36 minutes, and then gradually decrease the temperature. The control parameters were set as follows. P = 20, I = 40, D = 10, Ct = 1, SSP = 30, SP1 = 850, TM1 = 0.01, SP2 = 850, TM2 = 1.0, SP3 = 350, TM3 = 0.3, SP4 = 100, TM4 = 3, SP5 = 50, TM5 = off.

  Six disc samples were placed in a furnace at room temperature. A disk sample was placed near the end of the furnace and lowered about 2 inches (50.8 mm) from the door in front of the furnace. The hood door was left open and the hood fan was started before the test began. After closing the furnace door, the program was run and each batch test took about 1 hour to complete. The furnace temperature was monitored over time and compared to a standard curve.

  After running the furnace program and the temperature dropped to 50 ° C. (usually about 3 hours), the sample was removed from the oven and quickly cooled to room temperature. A second set of thickness and diameter measurements was made. The amount of% diameter shrinkage was calculated by dividing the difference between the average sample diameter before the test and the average sample diameter after the test by the average sample diameter before the test and multiplying by 100. The amount of% thickness shrinkage was calculated by dividing the difference in thickness before and after being burned in the oven by the thickness before burning and multiplying by 100. These values were averaged over three samples for each composition shown in Table 1. The shrinkage of the refractory cord gypsum product must be less than 5%.

  The above results show that good expansion in thickness is obtained when there is an expanding material only in the expanding layer of the gypsum panel. Furthermore, less swelling material is required to achieve a certain level of shrinkage reduction compared to dispersing the swelling material throughout the sample. A negative value for the average thickness shrinkage indicates that the sample expanded beyond the original thickness of the sample after the burn test. Samples 2 and 3 show a decrease in shrinkage with increasing amount of expanding material. The amount of expandable material in the expandable layer alone is increased over Sample 4-7. The best results are obtained with samples 6 and 7, even though less vermiculite was used compared to sample 3 with a homogeneous gypsum layer. Samples 4 and 5 with 40 g and 80 g, respectively, had much smaller shrinkage than sample 2 with 100 g vermiculite. Increasing the concentration of the inflatable material in the surface inflating layer uses the expansion more effectively and at a lower cost compared to distributing it homogeneously in the gypsum core. Become.

  While specific embodiments of intumescent layers for gypsum panels have been shown and described, as indicated in the claims and in its broader aspects, changes and modifications may be made therefor without departing from the invention, It will be apparent to those skilled in the art. It should be noted that the features of the present invention can be used with each other in any combination.

DESCRIPTION OF SYMBOLS 10 Multilayer gypsum panel 12 Core 14 Expanding layer 16 Surface finishing material 20 Surface 22 Surface 24 End 26 End 30 Panel 32 Fixture 34 Base 40 End coating 42 Gap

Claims (20)

A core comprising gypsum and a high temperature shrink resistant material and formed into a panel having at least two opposing faces and two opposing edges;
An intumescent layer covering at least a portion of the group consisting of one or more of the surfaces, one or more of the edges, and combinations thereof and comprising a gypsum matrix having a higher density than the core and a first intumescent material; and A multilayer gypsum panel comprising a surface finishing material covering at least a part of the expandable layer.   The panel of claim 1 wherein the high temperature shrink resistant material is at least one of the group consisting of glass fiber, fume silica, diatomaceous earth and clay.   The panel of claim 1, wherein the first expanding material comprises at least one of the group consisting of calcium sulfate anhydrite II, vermiculite, wollastonite, graphite and mica.   The panel of claim 1, wherein the expanding layer covers substantially all of one of the faces.   The panel of claim 1, wherein the expanding layer covers substantially all of the edges.   The panel of claim 4, wherein the inflating layer covers substantially all of the edges.   The panel of claim 1 wherein the facing material covers both at least one of the faces and the opposite end.   The panel of claim 7, further comprising an end coating comprising a second intumescent material and disposed over at least a portion of one of the ends and between the facing material and the inflatable layer. The panel of claim 1 having a total density of about 1800 to about 2600 Lb / 1000 ft ² (about 8.78 to 12.7 kg / m ² ) at a thickness of 5/8 inch.   The panel of claim 1 wherein the core has a total void volume greater than the expandable layer.   The panel of claim 1 wherein the core is essentially free of the first intumescent material.   The panel of claim 1 wherein the core comprises less than 0.2 wt% soluble salt. Producing a gypsum slurry comprising calcium sulfate hemihydrate, a high temperature shrink resistant material and water;
Dividing the gypsum slurry into at least a primary gypsum slurry and a secondary gypsum slurry;
Adding an expanding material to the secondary gypsum slurry to produce an expandable layer slurry;
A method of continuously forming a multilayer panel comprising forming a gypsum core from a primary gypsum slurry; and spreading a slurry of an expandable layer over at least a portion of a surface finish material.   14. The method of claim 13, further comprising adding the foam to the primary gypsum slurry after the dividing step.   14. The method of claim 13, further comprising applying an end coating to the inside of the surface finish material prior to the spreading step. Producing a primary slurry without a swelling material comprising a first amount of calcium sulfate hemihydrate, a first shrink resistant material and water;
Producing a secondary slurry comprising a second amount of calcium sulfate hemihydrate, a second shrink resistant material and an expanding material;
A method of manufacturing a gypsum panel, characterized by pouring a primary slurry over a first surface finish material; and pouring a secondary slurry over the primary slurry.   The method of claim 16, wherein the first shrink resistant material is the same as the second shrink resistant material.   The method of claim 16, further comprising disposing a second surface finish material adjacent to the secondary slurry.   19. The method of claim 18, wherein the second surface finish material is the same as the first surface finish material.   The method of claim 16, wherein the second pouring step comprises covering at least one face and at least one end with a secondary slurry.

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